JP4844114B2 - Method for manufacturing liquid discharge head and liquid discharge head - Google Patents

Description

  The present invention relates to a method for manufacturing a liquid discharge head and a liquid discharge head manufactured thereby.

  The ink jet recording system is one of non-impact recording systems, which can perform high-speed recording and can record on various recording media, and can obtain high-definition images. Because of these advantages, the inkjet recording system has been rapidly spread while expanding its use in recent years as a recording means for copying machines, photographs, various printing, industrial high-definition patterning as well as printers as peripheral devices for computers. ing.

  Such a recording head is provided with a nozzle for causing a liquid such as ink to fly and an energy generating means for applying energy for discharging to the liquid such as an ink in a pressure generating chamber communicating with the nozzle. A liquid discharge head using a piezoelectric element (piezo element), which is an electromechanical conversion element as energy generating means, controls the meniscus of the nozzle tip by the propagation of pressure waves generated by the piezoelectric element and discharges a droplet. Thus, a diaphragm for propagating the mechanical energy of such a piezoelectric element to the liquid is provided.

  When the diaphragm is deformed by disposing the electromechanical conversion element on the diaphragm, the amount of deformation can be easily increased as the thickness of the diaphragm decreases. Therefore, it is preferable to make the diaphragm as thin as possible so that the diaphragm can be efficiently deformed and ink can be ejected efficiently.

  Moreover, the thickness of the diaphragm is required to be uniform. For example, if there are multiple nozzles and the diaphragm thickness is not uniform, unevenness in the amount of deformation of the diaphragm provided in each nozzle will cause uneven ink droplets to be ejected, resulting in poor recording quality. become.

  However, the present situation is that the thickness of the diaphragm is not sufficiently satisfied in terms of handling and required uniformity of the thickness.

  Known examples of such diaphragms include:

  First, an ejection head as an example includes a body plate composed of a silicon single crystal substrate in which a pressure generation chamber, an ink supply channel, and a nozzle opening constituting an ink channel are integrally formed, and a silicon single crystal substrate. A vibration plate in which a silicon compound is formed on the surface of a metal material having the same thermal expansion coefficient is provided, and the body plate and the silicon compound forming surface of the vibration plate are joined without an adhesive layer (for example, Patent Documents) 1).

The ejection head as the next example includes a body plate having a pressure generating chamber and a nozzle, a quartz diaphragm bonded to the body plate, a piezoelectric element having an electrode layer and a piezoelectric film laminated on the quartz diaphragm. The quartz diaphragm has a cation layer at the junction with the body plate, and is anodically bonded to the body plate through the cation layer (see, for example, Patent Document 2).
Japanese Patent No. 3218664 JP 2005-144822 A

  In Patent Document 1, as a diaphragm, Pyrex (registered trademark) glass having a thickness of 20 μm to 100 μm or 42 alloy (Fe—Ni alloy) in which a thin film of Si oxide is formed is cited as an example. Since these glasses and alloys are very thin, it is fully expected that they will not be easy to handle when they are bonded to the body plate, but the contents regarding this are not described.

  In the prior art disclosed in Patent Document 2, the quartz diaphragm is anodically bonded to a body plate having a pressure generating chamber and a nozzle, and is then sliced to 10 μm or less by polishing. Therefore, a polishing process for thinning the quartz diaphragm is required. In this polishing process, it is necessary to remove the grease containing the polished abrasive particles and polished quartz particles, and the mixing of particles from the nozzle holes and the like into the flow path inside the discharge head, and the pressure generating chamber portion is hollow. Therefore, it is expected that the diaphragm will be depressed in the direction of the cavity when thinning. Therefore, in order to form a diaphragm having a uniform thickness without mixing abrasive particles or the like, it is sufficiently expected that the manufacturing process is complicated and difficult.

  In recent years, since a great advantage that patterning can be performed directly on a substrate or the like has occurred, industrial patterning applications using an ink jet recording method are widely considered. For example, in the case of patterning on a substrate, it is desired to increase the definition so that the landing diameter is 30 μm or less. To meet this demand, the diameter of the ink droplets ejected from the recording head is approximately 15 μm or less. It is said that it is necessary.

  The present invention has been made in view of the above problems, and the object of the present invention is to provide a thin and uniform diaphragm that can be deformed efficiently and with little variation in deformation amount on the body plate. It is an object of the present invention to provide a method of manufacturing a liquid discharge head that is easily provided, and to provide a liquid discharge head that is easy to manufacture and stable in quality by this manufacturing method.

  Said subject is solved by the following structures.

1. A nozzle for discharging liquid as droplets from the discharge hole;
A pressure chamber groove serving as a pressure chamber communicating with the nozzle;
A diaphragm covering the pressure chamber groove;
In the method of manufacturing a liquid ejection head having an electromechanical conversion element on the surface opposite to the pressure chamber groove side of the diaphragm,
A film forming step of the surface shape to form a film serving as the diaphragm in contact on the mirror surface of the holding substrate which is a mirror shape,
A bonding step of bonding a surface of the body plate in which the pressure chamber groove is formed with the surface on which the pressure chamber groove is formed and a surface on which the film on the holding substrate is formed;
Separated by peeling the supporting substrate from the film by separating the said holding substrate and the film have a a removal step of removing the holding substrate,
A method of manufacturing a liquid discharge head , comprising: providing the electromechanical conversion element on the film after the holding substrate is removed .

2. 2. The method of manufacturing a liquid ejection head according to 1, wherein the film forming step forms a metal film serving as the vibration plate on the mirror surface of the holding substrate .

3. 2. The method of manufacturing a liquid discharge head according to 1, wherein the film forming step forms a resin film made of a polyimide resin serving as the vibration plate on the mirror surface of the holding substrate .
4). The film forming step forms a metal film to be the diaphragm on the mirror surface of the holding substrate,
The bonding step includes buffing each of the bonding surfaces of the metal film and the surface of the body plate where the pressure chamber grooves are formed to make the surface roughness Ra <10 nm. 2. The method of manufacturing a liquid discharge head according to 1, wherein both polishing surfaces of the holding substrate are brought into contact with each other and pressure is applied to bond both of them to each other.
5. 5. The method of manufacturing a liquid discharge head according to any one of claims 1 to 4, wherein an activation process for improving the adhesion of the film is not performed on the mirror surface of the holding substrate. .

6 . The method of manufacturing a liquid discharge head according to any one of 1 to 5 , wherein the nozzle is formed on a body plate in which the pressure chamber groove is formed.

7 . A nozzle plate in which the nozzles are formed, a manufacturing method of the liquid discharge head according to any one of 1 to 6, characterized in that it comprises a step of joining the body plate, wherein the pressure chamber groove is formed.

8 . The method of manufacturing a liquid discharge head according to any one of 1 to 7 , wherein the body plate is made of Si.

9 . The method of manufacturing a liquid discharge head according to any one of 1 to 8 , further comprising a step of providing a SiO ₂ layer on a surface where the discharge hole of the nozzle exists.

10 . 8. The method of manufacturing a liquid discharge head according to 7 , wherein the nozzle plate is made of glass or resin having a volume resistivity of 10 ¹⁵ Ω · m or more.

11 . The method for manufacturing a liquid discharge head according to any one of 1 to 10 , further comprising a step of performing a liquid repellent treatment on the outermost surface where the discharge holes of the nozzles are present.

12 . A liquid discharge head manufactured by the manufacturing method according to any one of 1 to 11 .

13 . An electrostatic voltage applying means for generating an electrostatic attraction force by forming an electric field between the liquid in the nozzle and a substrate provided opposite to the surface on which the discharge hole exists; 13. The liquid discharge head according to 12 , wherein

  In the inventions according to claims 1 and 10, even if the diaphragm is a thin film that is expected to be difficult to handle, the thin film that becomes the diaphragm is held by the holding substrate, so that it is wrinkled or broken. Since the pressure chamber can be easily formed by covering the pressure chamber groove of the body plate without being damaged, the deformation energy of the electromechanical transducer provided on the diaphragm is efficiently obtained. It is transmitted to the liquid in the pressure chamber, and the droplets can be efficiently discharged. Accordingly, it is possible to provide a method for manufacturing a liquid discharge head in which a vibration plate can be easily provided on the body plate, and to provide a liquid discharge head with stable quality by this manufacturing method.

  Hereinafter, embodiments of a liquid discharge head according to the present invention will be described with reference to the drawings.

  FIG. 6 is a diagram illustrating an overall configuration of a liquid ejection apparatus S that uses a liquid ejection head A (cross-sectional view) as an example of the present embodiment. The liquid discharge head A can be applied to various liquid discharge apparatuses such as a so-called serial method or line method.

  The liquid ejection apparatus S includes a liquid ejection head A in which a nozzle 10 that ejects a droplet D of a chargeable liquid L such as ink from an ejection hole 13 is formed, an operation control unit E, and an ejection hole of the liquid ejection head A. And a counter electrode 3 that supports a base member K that receives the landing of the droplet D on the counter surface.

  On the side facing the counter electrode 3 of the liquid discharge head A, a body plate 2 having a plurality of nozzles 10 and a pressure chamber 24 formed by laminating a thin plate 1 communicating with each of these nozzles is provided. The body plate 2 is preferably made of Si that can easily form a fine shape. The liquid discharge head A has a flat discharge surface 12 from which the nozzle 10 does not protrude from the discharge surface 12 facing the counter electrode 3 or from which the nozzle 10 protrudes only about 30 μm. Further, the discharge hole 13 of the nozzle 10 may have a polygonal shape, a star shape, or the like, instead of being formed into a circular cross-sectional shape. The diameter when the cross-sectional shape is not a circle is the diameter when the cross-sectional area of the target cross-section is replaced with a circle having the same area. The internal diameter of the discharge hole 13 is referred to as the nozzle diameter.

  Further, in the liquid discharge head A shown in FIG. 6, the inner peripheral surface 17 of the nozzle 10 of the body plate 2 and the bottom surface 18 of the pressure chamber 24 subsequent thereto are charged with the liquid L in the nozzle made of a conductive material. A charging electrode 16 as an electrostatic voltage applying means is provided. Further, each charging electrode 16 is connected to an electrostatic voltage power source 63 by a wiring (not shown). By providing the charging electrode 16 in this way, the charging electrode 16 comes into contact with the liquid L inside all the pressure chambers 24 of the body plate 2, and the electrostatic voltage power source 63 applies static electricity to the charging electrode 16. When an electric voltage is applied, the liquid L in all the nozzles 10 is charged at the same time, and an electrostatic attraction force is generated between the liquid discharge head 2 and the counter electrode 3, particularly between the liquid L and the substrate K. Can be done.

  Further, the thin plate 1 that covers the pressure chamber groove and serves as the pressure chamber 24 is made of metal or resin and functions as a vibration plate for forming a meniscus in the liquid L, and is deformed so as to generate pressure in the liquid L. It is possible.

  On the surface of the thin plate 1 opposite to each pressure chamber 24, a piezoelectric element 22 that is a piezoelectric element actuator is provided as an electromechanical conversion element as a pressure generating unit, and the piezoelectric element 22 includes the piezoelectric element 22. A driving voltage power source 61 is connected to apply a driving voltage to the piezoelectric element 22 to deform it. The piezo element 22 is deformed by the application of the drive voltage from the drive voltage power supply 61 to generate a pressure on the liquid L in the nozzle 10 to form a meniscus of the liquid L in the discharge hole 13 of the nozzle 10. Yes. In addition to the piezoelectric element actuator as in this embodiment, for example, an electrostatic actuator can be adopted as the pressure generating means.

  The drive voltage power supply 61 and the electrostatic voltage power supply 63 for applying an electrostatic voltage to the charging electrode 16 are connected to the operation control means E, respectively, and are controlled by the operation control means E, respectively.

  The operation control means E is composed of a computer in which a CPU 51, a ROM 52, a RAM 53, etc. are connected by a BUS (not shown). The CPU 51 is based on a power supply control program stored in the ROM 52, The driving voltage power supply 61 is driven to discharge the liquid L from the discharge hole 13 of the nozzle 10.

  Here, the liquid discharge head A will be described in detail with reference to FIG. A thin plate 101 is attached to the body plate 102 in FIG. 1A to connect a pressure chamber groove 124 serving as a pressure chamber, a common channel groove 122 serving as a common channel, and a common channel and a pressure chamber. A channel groove 123 serving as a channel is provided. Hereinafter, the reference numerals of the pressure chamber groove, the supply path groove, and the common ink chamber groove used in the above description are also used for the pressure chamber, the supply path, and the common ink chamber, respectively.

  The common channel groove 122 is provided with a supply port 125 through which a supply pipe for supplying liquid from an external liquid tank (not shown) is connected, and is supplied by a supply pump (not shown) or by a differential pressure depending on the position of the liquid tank. A predetermined supply pressure is applied to the liquid such as the common flow path 122, the pressure chamber 124, and the nozzle 110 through the pipe and the supply port 125.

  A nozzle 110 for discharging ink is formed on the bottom surface of the pressure chamber groove 124. By attaching the thin plate 101 and the body plate 102 together, the flow path unit 10M is formed.

  FIG. 1B shows a cross section of the periphery of one pressure chamber groove 124 at the position YY ′ of the thin plate 101 and the position XX ′ of the body plate 102 in the liquid discharge head 10A shown in FIG. Is schematically shown. As shown in FIG. 1A, the piezoelectric element 103 is bonded to the flow path unit 10M as an ink ejection actuator to the back surface of each pressure chamber 124 opposite to the surface to which the body plate 102 of the thin plate 101 is bonded. Thus, the liquid discharge head 10A is completed.

A drive pulse voltage is applied to each piezoelectric element 103 of the liquid discharge head 10A, and vibration generated from the piezoelectric element 103 is transmitted to the pressure chamber 124 through the thin plate 101, and the pressure of the ink in the pressure chamber 124 is changed to discharge. A meniscus is formed in the hole 113. In FIG. 1B, reference numeral 141 denotes an adhesive layer that bonds the thin plate 101 and the body plate 102, 143 denotes an SiO ₂ layer that will be described later, and 128 denotes to suppress the bleeding of ink from the ejection holes 113. The liquid repellent layer is shown. By providing the liquid repellent layer 128, the liquid meniscus formed in the discharge hole 113 portion of the nozzle 110 is hardly spread on the discharge surface around the discharge hole 113, thereby effectively reducing the electric field concentration at the meniscus tip. Can be prevented.

  FIG. 2 schematically shows an example of a manufacturing process for manufacturing the liquid discharge head as shown in FIG. It is preferable to form a body plate 202 of a liquid discharge head composed of a nozzle 210 and a common channel groove (not shown), a channel groove, and a pressure chamber groove 224 from a Si substrate by a known photolithography process and etching process. (FIG. 2 (1a)). By using the Si substrate, the nozzle, the pressure chamber groove 224 and the like can be easily manufactured with high accuracy.

An SiO ₂ film 243 having a thickness of about 0.5 μm to 300 μm is preferably formed on the surface of the body plate 202 where the discharge holes 213 are formed. By providing the SiO ₂ film 243, the electric field can be efficiently concentrated on the meniscus formed in the discharge hole 213. The method for forming the SiO ₂ film 243 is not particularly limited, and examples thereof include thermal oxidation treatment and TEOS (tetraethoxysilane) treatment.

  Further, a charging electrode 216 made of a conductive material such as NiP, Pt, or Au is provided on the inner peripheral surface of the nozzle 210 of the body plate 202 and the subsequent bottom surface of the pressure chamber groove 224 (FIG. 2 (1b)). . The method for providing the charging electrode 216 is not particularly limited, and a known vacuum deposition method, sputtering method, or the like may be used. Further, the conductive material is not limited to the above example, and a material that does not cause corrosion or the like by being in contact with the liquid used for ejection may be selected as appropriate.

  Next, for example, a Si substrate is used as the holding substrate 270 (FIG. 2 (2a)), and a thin film (thin plate) 201 serving as a vibration plate is provided on the holding substrate 270 (FIG. 2 (2b)). The thin film 201 is preferably a highly durable metal or an easily manufactured and inexpensive resin. The thickness of the thin film 201 serving as the vibration plate may be appropriately determined from the viewpoints of handling and specifications such as deformation force and responsiveness in a practical driving voltage range of the piezoelectric element 203, but is usually about 1 μm to 50 μm. Is preferred.

  The film thickness is desirably uniform, and is more preferably ± 20% or less, and even more preferably ± 10% or less of the film thickness. As a method of providing the thin film 201 having a uniform thickness with the above-described film thickness, when the thin film 201 is a metal, a vacuum film formation such as a sputtering method or a vacuum evaporation method, a plating process, an electroforming process, or the like is used. Examples of the method include a spin coating method, a dip coating method, and a spray coating method. By using these methods, the degree of uniformity of the film thickness can be ± 10% or less of the film thickness.

  When the metal or resin thin film 201 as described above is provided on the holding substrate 270, it is preferable not to perform an activation process for improving the adhesion of the thin film 201 to the substrate 270. By not performing this activation treatment, for example, a thin film made of electroforming or resin formed on the holding substrate 270 that is a Si substrate does not have a strong adhesion to the Si substrate, and will be described later. When removing the Si substrate, the Si substrate can be easily removed from the thin film 201.

  Since the surface shape of the holding substrate 270 is transferred to the thin film 201 made of a metal or a resin to be the above-described vibration plate, for example, if there are irregularities or scratches, the vibration plate has that shape. The vibration plate with the irregularities and scratches transferred may be cracked due to the transferred irregularities and scratches due to vibrations applied over a long period of time, resulting in damage. Since it is sufficiently predicted, the surface shape of the holding substrate 270 is preferably a mirror surface.

  The material of the holding substrate 270 is not particularly limited, but can be a mirror surface as described above, and is preferably a material that can withstand heating at the time of bonding described later. Examples include a substrate, a SUS (Special Use Stainless Steel) plate, and a quartz substrate.

  Next, the film surface of the holding substrate 270 on which the thin film 201 made of metal or resin is formed and the surface on which the groove of the body plate 202 is formed are bonded with an adhesive 241 (FIG. 2 (e) )).

  Here, the bonding method is not particularly limited, but an anodic bonding method which is a bonding method between Si and borosilicate glass containing mobile ions, in addition to using the widely used adhesive 241 shown in FIG. (FIG. 3), there are an intermolecular force bonding method (FIG. 4) by an intermolecular force in which nothing is interposed between objects to be bonded, and a metal bonding method between metals (FIG. 5).

  By using these methods, the body plate and the thin plate can be firmly bonded. These anodic bonding method, intermolecular force bonding method and metal bonding method will be described below.

First, the joining of the thin plate 1 and the body plate 2 using the anodic bonding method will be described with reference to FIG. In the case where two substrates are bonded using an anodic bonding method, one of the substrates may be Si, and the other may be a borosilicate glass containing mobile ions, typically sodium ions (Na ⁺ ).

  Specific examples of borosilicate glass containing mobile ions (hereinafter referred to as borosilicate glass) include Pyrex (registered trademark) and Tempax Float (registered trademark). For example, when the body plate 302 is made of Si but the thin plate 301 is made of metal, anodic bonding cannot be performed as it is. In order to cope with this, it is possible to cope with this by providing a borosilicate glass layer 341 on the surface of the thin plate 301 to be bonded to the body plate 302 (FIG. 3 (2b)).

  The film thickness of the borosilicate glass layer 341 may be a film thickness that can be strongly bonded by anodic bonding, and is preferably 1 μm or more from the viewpoint of the density and uniformity of the film. The thickness is preferably 5 μm or less from the viewpoint of applied voltage and from the prevention of cracking due to internal stress of the film.

  The borosilicate glass layer 341 can be formed by any one of a vacuum deposition method, a radio frequency (RF) magnetron sputtering method, and an ion plating method, and the substrate temperature can be easily formed at the time of film formation. It is preferable to heat so that it may become 250 degreeC or more. The upper limit of the temperature is not particularly defined, but is preferably about 400 ° C. from the viewpoint of a substrate mounting jig, a substrate temperature control device during film formation, and the like.

  Next, the holding substrate 370 having the thin plate 301 on which the borosilicate glass layer 341 described above is formed and the body plate 302 are overlapped and fixed in an appropriate positional relationship, and the body plate 302 and the borosilicate glass are fixed. The temperature of the junction with 341 is set to a range of 300 ° C. to 550 ° C., and a voltage is applied using a DC high-voltage power supply 310 (the body plate 302 is positive (+) and the thin plate 301 side is negative (−). And 5V / 1 μm to 20 V / 1 μm), and anodic bonding can be performed (FIG. 3E).

  Next, the intermolecular force bonding method will be described with reference to FIG. For example, each surface (442 and 443) for bonding a Pt (platinum) thin plate 401 provided on a Si substrate which is a holding substrate 470 and a body plate 402 made of Si is diamond paste (particle size is approximately 0.1 μm to 0 μm). Polishing is performed so that the surface roughness Ra <10 nm.

  Here, the surface roughness Ra in the present embodiment is measured using a stylus type surface roughness meter Dektak3030 (manufactured by Sloan Technology Veeco Instruments, stylus: diamond radius 12.5 μm, stylus pressure: 0.05 mN). The arithmetic average value of each surface roughness at any three locations with a width of 3 mm is used. Next, when the polishing surface 442 of the Pt layer 401 on the holding substrate 470 is directed upward and the polishing surface 443 of the body plate 402 is brought into contact with this surface and the entire surface of the body plate 402 is pressed almost uniformly, They are joined by force (FIG. 4E). During the bonding, the bonding surface can be heated more effectively by heating from about 200 ° C. to about 500 ° C., but heating is not always necessary. When the nozzle plate is made of resin, the heating temperature needs to be lower than the softening point of the resin.

  The material capable of performing intermolecular force bonding is not particularly limited, and can be bonded if the surfaces to be bonded (442 and 443) can each have a surface roughness Ra <10 nm.

  Next, the metal bonding method will be described with reference to FIG. Metal bonding is performed by bonding gold (Au), gold-tin (Au—Sn) alloy, or indium (In) to the bonded surfaces of the nickel thin plate 501 and the body plate 502 on the Si substrate surface to be bonded, for example, the holding substrate 570. The metal layers (546 and 547) are provided by using the same material appropriately selected from any one of the above), and the metal layers (546 and 547) are overlapped with each other, and then the stacked metal layers are pressurized while being heated. Can be joined together. The heating temperature of the joint is preferably about 400 ° C. for gold, about 200 ° C. for gold-tin alloy, and about 100 ° C. for indium.

  For example, referring to FIG. 2, the holding substrate 270 is removed after bonding the body plate 202 and the thin plate (film) 201 provided on the holding substrate 270 by the bonding method described above. As described above, when the thin plate 201 is provided on the holding substrate 270, since the activation process for improving the adhesion to the holding substrate 270 is not performed, the holding substrate 270 does not perform any special process. By separating the plate 202 and the holding substrate 270 from each other, they can be easily peeled off and removed from the thin plate 201 fixed to the body plate 202 (FIG. 2 (f)).

  Therefore, the thin plate 201 fixed by the above bonding method is present on the body plate 202. The method for removing the holding substrate 270 is not particularly limited to the above method, and any method may be used as long as it is a method that removes the body plate 202 and the thin plate 201 without damaging them. For example, a Si substrate may be dissolved. . Further, in the case of other bonding methods shown in FIGS. 3 to 5, the holding substrate may be removed in the same manner as described above with reference to FIG.

  Thereafter, for example, referring to FIG. 2, the liquid discharge head 20 </ b> A can be completed by providing the thin plate 201 with the piezoelectric elements 203 corresponding to the respective pressure chambers 224. The liquid ejection head can be completed by providing the thin plate shown in FIGS. 3 to 5 with the piezoelectric element as described above with reference to FIG. 2 as an example.

  In FIG. 2, a liquid repellent layer 228 is provided on the discharge surface where the nozzle discharge hole 213 is provided. For the liquid repellent layer 228, for example, a material having water repellency is used if the liquid is aqueous, and a material having oil repellency is used if the liquid is oily, but in general, FEP (ethylene tetrafluoride. Fluorine resin such as propylene fluoride), PTFE (polytetrafluoroethylene), fluorine siloxane, fluoroalkylsilane, and amorphous perfluoro resin is often used, and is formed on the discharge surface by a method such as coating or vapor deposition. . The liquid repellent layer 228 may be formed directly on the ejection surface, or may be formed via an intermediate layer in order to improve the adhesion of the liquid repellent layer 228. In addition, a liquid repellent layer can be provided on the ejection surface shown in FIGS. 3 to 5 in the same manner as described above with reference to FIG.

  The body plate shown in FIGS. 2 to 5 preferably has a structure in which a portion having a nozzle and a portion having a pressure chamber groove or the like are integrated. By adopting this integrated configuration, the mutual positions of the nozzle and the pressure chamber groove can be easily formed with high accuracy. Further, it is preferable that the portion having the nozzle 710 shown in FIG. 7 is a nozzle plate 702b, and the portion having the pressure chamber groove 724 and the like is a body plate 702a. By separating the nozzle plate and the body plate, it is possible to select a material suitable for each of the necessary characteristics, processing accuracy, ease of manufacture, and the like.

When the nozzle plate and the body plate are separated from each other, the body plate 702a is preferably made of Si with good processing accuracy, and the nozzle plate 702b is made of a glass having a volume resistivity of 10 ¹⁵ Ω · m or more ( Hereinafter, it is preferably formed from a resin having a volume resistivity of 10 ¹⁵ Ω · m or more (hereinafter referred to as a high resistance resin). As the high resistance glass, for example, quartz, synthetic quartz, high purity glass, or the like may be selected as appropriate. As the high resistance resin, for example, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PI (polyimide), or the like may be selected as appropriate. It ’s fine.

  A method for producing a nozzle plate by providing a nozzle in high resistance glass is not particularly limited. For example, a dry glass using a high resistance glass substrate and a carbon fluoride gas or a hydrofluoric carbon gas as a reaction gas is used. There is a method of performing an etching process. Further, a method for producing a nozzle plate by providing a nozzle in a high-resistance resin is not particularly limited, and examples thereof include a resin molding method and a method using a known photolithography technique for a coated resin film.

  The bonding of the body plate 702a and the thin plate 701 is not particularly limited, and may be the same as the adhesive, anodic bonding method, intermolecular force bonding method, metal bonding method, and the like described above. Further, the bonding between the body plate 702a and the nozzle plate 702b is not particularly limited, and the above-described methods and the like may be appropriately used.

The inventors configured the electric field strength of the electric field between the electrodes to be a practical value of 1.5 kV / mm using the liquid discharge experimental apparatus S ′ shown in FIG. In experiments conducted by forming the nozzle plate 11 ′ and based on the following experimental conditions, there were cases where the droplet D ′ was ejected from the nozzle 10 ′ and was not ejected.
[Experimental conditions]
Distance between discharge surface 12 'of nozzle plate 11' and facing surface of counter electrode 3 ': 1.0 mm
Nozzle plate 11 'thickness: 125 μm
Nozzle diameter: 10 μm
Electrostatic voltage: 1.5 kV
Drive voltage: 20V
The nozzle 10 ′ of the experimental liquid discharge head A ′ used in the liquid discharge experiment has a taper angle of 4 °. The taper angle indicates an angle that spreads in a direction away from the discharge surface 12 ′ from a perpendicular to the discharge surface 12 ′ in the cross section of the nozzle 10 ′. The taper angle has a small influence on the ejection, and it is obtained from simulations described later that the dependence on the conditions for ejecting the droplets stably is not large.

  Here, the principle of liquid ejection in the liquid ejection head will be described with reference to FIG. In the experimental liquid ejection head A ′, an electrostatic voltage is applied from the electrostatic voltage power source 63 ′ to the charging electrode 16 ′ as electrostatic voltage application means, and is opposed to the liquid L ′ in the ejection hole 13 ′ of the nozzle 10 ′. An electric field is generated between the facing surface of the electrode 3 ′ facing the experimental liquid ejection head A ′. Further, a driving voltage is applied from the driving voltage power supply 61 ′ to the piezoelectric element 22 ′ as pressure generating means to deform the piezoelectric element 22 ′, and thereby the discharge hole 13 ′ of the nozzle 10 ′ is generated by the pressure generated in the liquid L ′. To form a meniscus of liquid L ′.

  When the insulating property of the nozzle 10 ′ is increased, as shown by the equipotential lines by simulation in FIG. 9, the equipotential lines are arranged in the nozzle 10 ′ in the direction substantially perpendicular to the ejection surface 12 ′. A strong electric field is generated toward the meniscus portion.

  In particular, as can be seen from the fact that the equipotential lines 9-1 are dense at the tip of the meniscus in FIG. 9, a very strong electric field concentration occurs at the tip of the meniscus. For this reason, the meniscus is torn off by the electrostatic force of the electric field and separated from the liquid L ′ in the nozzle to form a droplet D ′. Further, the droplet D ′ is accelerated by the electrostatic force, and is attracted and landed on the base material K ′ supported by the counter electrode 3 ′. At that time, since the droplet D 'attempts to land closer by the action of electrostatic force, the angle at the time of landing on the substrate K' is stabilized and accurately performed.

  As described above, if the discharge principle of the liquid L ′ in the experimental liquid discharge head A ′ is used, the experimental liquid discharge head A ′ having a flat discharge surface also uses the nozzle 10 ′ portion having high insulation. By generating a potential difference in the vertical direction with respect to the discharge surface 12 ′, strong electric field concentration can be generated, and an accurate and stable discharge state of the liquid L ′ can be formed.

In the experiment using the liquid discharge experimental device S ′, the electric field strength at the tip of the meniscus was obtained for all cases where the droplet D ′ was stably discharged from the nozzle. Actually, since it is difficult to directly measure the electric field strength at the tip of the meniscus, the electric field simulation software “PHOTO-VOLT” (trade name, manufactured by Photon Co., Ltd.) was used for calculation. The electric field strength here refers to the electric field strength 300 seconds after voltage application in the current distribution analysis mode. As a result, in all cases, the electric field strength at the meniscus tip was 1.5 × 10 ⁷ V / m or more. In this experiment, even when the droplet D ′ was not stably ejected from the nozzle, the electric field strength at the meniscus tip was calculated by the same simulation as described above. As a result, it was less than 1.5 × 10 ⁷ V / m.

Further, as a result of calculating the electric field strength at the tip of the meniscus by inputting the same parameters as the above experimental conditions into the software, the electric field strength is the volume resistance of the insulator used for the nozzle plate 11 ′ as shown in FIG. It turned out to be strongly dependent on the rate. Moreover, in order to stably discharge the droplet D ′ from the nozzle 10 ′, it is obtained from the above experiment that the electric field strength at the tip of the meniscus needs to be 1.5 × 10 ⁷ V / m or more. Therefore, as apparent from FIG. 10, it was found that the volume resistivity of the nozzle plate 11 ′ should be 10 ¹⁵ Ω · m or more.

The characteristic dependency of the electric field strength at the tip of the meniscus on the volume resistivity of the nozzle plate 11 ′ as shown in FIG. 10 can be obtained in the same way even when simulation is performed with various nozzle diameters. In all cases, it is known that the electric field strength at the meniscus tip is 1.5 × 10 ⁷ V / m or more when the volume resistivity is 10 ¹⁵ Ω · m or more.

Therefore, in the liquid discharge head A shown in FIG. 6, it is preferable to provide the SiO ₂ layer 43 having a volume resistivity of about 1 × 10 ¹⁶ Ω · m on the discharge surface 12 of the body plate 2. By having the SiO ₂ layer 43, the required volume resistivity can be sufficiently satisfied, so that the electric field strength at the tip of the meniscus of the droplet formed in the discharge hole 13 is 1.5 × 10 ⁷ V / m. It can be over. Furthermore, the SiO ₂ layer 43 absorbs these liquids even if any of the discharged liquid is used, which is an inorganic liquid, an organic liquid, or a conductive paste containing a high electrical conductivity substance (such as silver powder). There is no need to worry about a decrease in volume resistivity. Accordingly, since the volume resistivity in the vicinity of the discharge surface 12 of the body plate A can maintain a required value, the electric field strength at the tip of the meniscus can be stabilized to 1.5 × 10 ⁷ V / m or more. Accordingly, the liquid can be stably discharged.

Further, the liquid discharge head 70A shown in FIG. 7 includes a nozzle plate 702b and a body plate 702a. In this case, it is preferable to provide the SiO ₂ layer 743 on the ejection surface 712 of the nozzle plate 702b as described above. Further, when the nozzle plate 702b is formed from high resistance glass or high resistance resin, the SiO ₂ layer 743 may not be provided. In the case where the SiO ₂ layer 743 is provided and the high resistance glass or the high resistance resin is used, the above required volume resistivity can be sufficiently satisfied, and the meniscus tip of the droplet formed in the discharge hole 713 The electric field strength of can be 1.5 × 10 ⁷ V / m or more.

  In addition, when the resin of the nozzle plate 702b absorbs a conductive liquid, the electrical conductivity of the nozzle plate 702b increases, and as a result, the volume resistivity may decrease. In such a case, a liquid absorption preventing layer may be provided on the surface of the nozzle plate 702b that contacts the liquid to be discharged.

  Further, when the nozzle 10 ′ of the nozzle plate 11 ′ shown in FIG. 8 has a cylindrical hole shape without a taper that has the same diameter as the discharge hole 13 shown in FIG. 6, the thickness of the nozzle plate 11 ′ is 10 μm. FIG. 11 shows the simulation results of the electric field strength at the meniscus tip when the nozzle diameter is changed as parameters of 20 μm, 50 μm, and 100 μm.

FIG. 11 shows that the electric field strength at the meniscus tip increases as the nozzle diameter decreases and the nozzle plate increases in thickness. In order to stably discharge the droplets D ′ from the nozzle 10 ′, the electric field strength at the meniscus tip must be 1.5 × 10 ⁷ V / m or more. In the case of 10 μm, droplets can be stably discharged by setting the nozzle diameter to less than 4 μm. Further, for example, when the nozzle plate thickness is 20 μm, the nozzle diameter is less than 6 μm, when the nozzle plate thickness is 50 μm, the nozzle diameter is less than 11 μm, and when the nozzle plate thickness is 100 μm, the nozzle diameter is When the thickness is less than 24 μm, the droplets can be stably discharged.

For example, when the nozzle diameter is 5 μm, the thickness of the nozzle plate 702b made of high resistance glass shown in FIG. 7 or the thickness of the SiO ₂ layer 43 provided on the discharge surface of the body plate 2 shown in FIG. 6 is about 20 μm or more. The droplet D can be discharged stably.

As described above, the thickness of the nozzle plate 702b made of high-resistance glass or the thickness of the SiO ₂ layer 43 provided on the discharge surface of the body plate 2 is set to a desired nozzle diameter with reference to FIG. By setting the value more appropriately, a liquid discharge head capable of stably discharging droplets can be obtained.

  In this embodiment, the meniscus formed by deformation of the piezo element 22 is separated by electrostatic attraction force into droplets, accelerated by an electric field due to electrostatic voltage, and landed on the substrate K. In addition to this, for example, it is possible to apply a driving voltage that is strong enough to cause the liquid L to form droplets only by the pressure due to the deformation of the piezoelectric element 22.

  Examples will be described below. Formation of 32 nozzles having a nozzle diameter of 10 μm on the discharge surface of the body plate, pressure chamber grooves on the opposite side, common flow channel grooves, flow channel grooves connecting the common flow channel grooves and the pressure chamber grooves, etc. The same known photolithography technique (resist application, exposure, development) and anisotropic dry etching technique using ICP (Inductively Coupled Plasma) are used in any of Examples 1 to 3 using a Si substrate. Formed using.

  In the liquid discharge experiment, a conductive liquid containing 3% by mass of a dye (CI Acid Red 1) in ethanol was used.

The anisotropic dry etching technique has a structure with a high aspect ratio (the ratio between the depth and width of the processed recess, and a high aspect ratio indicates a state where the depth of the groove is deep and the width is narrow). In order to protect the sidewalls of the recesses processed by etching during etching, a cycle for generating chemical species (radicals, ions, etc.) that cause an etching reaction and the sidewalls are protected. This is an etching process in which a cycle for depositing a protective film is alternately performed. By using this anisotropic dry etching technique, the side wall of the recess formed in the silicon substrate can be processed perpendicular to the substrate surface. In this embodiment, SF ₆ was used as an etching gas for forming grooves and holes, and C ₄ F ₈ was used as a deposition gas for the sidewall protective film.

Example 1
A description will be given along the manufacturing process shown in FIG. A groove is formed in the body plate 202 made of Si (FIG. 2 (1a)), and TEOS (tetraethoxy) is formed on the discharge surface where the discharge hole 213 of the nozzle 210 is opposite to the surface where the groove is formed. A SiO ₂ film 243 having a thickness of about 60 μm was formed by silane treatment. Further, a NiP film is used as the charging electrode 216 on the inner peripheral surface of the nozzle 210 and the bottom of the pressure chamber by using the RF magnetron sputtering method, the substrate temperature is 300 ° C., the high frequency power is 500 W (frequency: 13.56 MHz), and the atmosphere is argon (0. 667 Pa), a film having a thickness of 0.5 μm was formed (FIG. 2 (1 b)).

  Next, nickel is deposited on the surface of a separately prepared Si substrate 270 (FIG. 2 (2a)) by using a magnetron sputtering method without performing activation treatment, and this is used as an electrode for electroforming. 25 μm nickel 201 was electroformed (FIG. 2 (2 b)).

  Next, after the nickel electroformed film 201 on the Si substrate 270 is bonded to the groove forming surface of the body plate 202 produced previously using the epoxy adhesive 241 (FIG. 2E), the body plate 202 By separating the Si substrate 270, the nickel electroformed film 201 and the Si substrate 270 can be easily peeled off (FIG. 2 (f)). After the Si substrate 270 is removed, the nickel electroformed film 201 becomes the body plate 202. It is in a state of being fixed with an adhesive 241.

Thereafter, a liquid repellent film layer 228 is formed on the SiO ₂ film 243 on the discharge surface side of the body plate 202 by using Evaporation Substrate WR1 (water repellent film material for vacuum deposition), and the pressure chamber 224 portion is formed. A piezoelectric element 203 having a thickness of 50 μm was attached to the covered thin plate portion of nickel electroforming to complete the ejection head 20A (FIG. 2G).

  Next, the piezoelectric element 203 and the charging electrode 216 of the ejection head 20A are connected to an electrostatic voltage power source (electrostatic voltage 1.5 kV) and a drive voltage power source (drive voltage 20 V) including operation control means, and the ejection head 20A. The distance between the discharge surface and the counter electrode was set to 1 mm. After that, when the ejection head 20A was operated for about one month, the ejection of the ink droplets from the 32 ejection holes was not observed, and there was no inconvenience that the liquid volume was uneven or the liquid amount was uneven. It was confirmed to work.

(Example 2)
The manufacturing process shown in FIG. 4 will be described. Grooves are formed in the body plate 402 made of Si (FIG. 4 (1a)), and TEOS (tetraethoxysilane) is formed on the discharge surface having the nozzle discharge holes 413 opposite to the surface on which the grooves are formed. ) A SiO ₂ film 443 having a thickness of about 60 μm was formed by the treatment. Further, a NiP film is used as the charging electrode 416 on the inner peripheral surface of the nozzle 410 and the bottom of the pressure chamber, using an RF magnetron sputtering method, the substrate temperature is 300 ° C., the high-frequency power is 500 W (frequency: 13.56 MHz), and the argon atmosphere (0. 667 Pa) to a thickness of 0.5 μm (FIG. 4 (1 b)).

  Next, a Pt (platinum) film 401 having a thickness of about 1 μm was formed 401 on the surface of a separately prepared Si substrate 470 (FIG. 4 (2a)) by magnetron sputtering without performing an activation process (FIG. 4 (2b)).

Next, the bonding surface 442 of the Pt film 401 and the bonding surface 443 of the body plate 402 were buffed so that the surface roughness was Ra <10 nm. Thereafter, the positional relationship between the Si substrate 470 having a Pt film and the body plate 402 was adjusted, both polished surfaces were brought into contact with each other, and a pressure of 2.94 × 10 ⁴ Pa was uniformly applied to the entire surface. It was assumed that the intermolecular bonding between the body plate 402 and the Pt film 401 was completed when about 10 minutes had elapsed from the start of pressurization with reference to a bonding experiment conducted in advance (FIG. 4E).

  Next, by separating the Si substrate 470 from the body plate 402, the Pt film 401 and the Si substrate 470 can be easily separated (FIG. 4F). After the Si substrate 470 is removed, the Pt film 401 is It is in a state of being fixed to the body plate 402 by intermolecular force (FIG. 4 (f)).

Thereafter, a liquid repellent film layer 428 is formed on the SiO ₂ film 443 on the discharge surface side of the body plate 402 by using Evaporation Substrate WR1 (water repellent film material for vacuum deposition) of Merck Japan, and the pressure chamber 424 portion is formed. The piezoelectric element 403 having a thickness of 50 μm was attached to the thin plate portion of the Pt film covered, thereby completing the ejection head 40A (FIG. 4G).

  Next, the piezoelectric element 403 and the charging electrode 416 of the ejection head 40A are connected to an electrostatic voltage power source (electrostatic voltage 1.5 kV) and a drive voltage power source (drive voltage 20 V) including operation control means, and the ejection head 40A. The distance between the discharge surface and the counter electrode was set to 1 mm. After that, when the ejection head 40A was operated for about one month, the ink droplets from the 32 ejection holes were not ejected, and there were no problems such as unevenness in the liquid amount. It was confirmed to work.

(Example 3)
Since this embodiment is the same manufacturing process as Example 1 described along FIG. 2 except that the thin film 201 provided on the Si substrate 270 is a polyimide resin, it will be described along FIG.

A groove is formed in the body plate 202 made of Si (FIG. 2 (1a)), and TEOS (tetraethoxy) is formed on the discharge surface where the discharge hole 213 of the nozzle 210 is opposite to the surface where the groove is formed. A SiO ₂ film 243 having a thickness of about 60 μm was formed by silane treatment. Further, a NiP film is used as the charging electrode 216 on the inner peripheral surface of the nozzle 210 and the bottom of the pressure chamber by using the RF magnetron sputtering method, the substrate temperature is 300 ° C., the high frequency power is 500 W (frequency: 13.56 MHz), and the atmosphere is argon (0. 667 Pa), a film having a thickness of 0.5 μm was formed (FIG. 2 (1 b)).

  Next, 3 μm of polyimide resin was applied to the surface of the separately prepared Si substrate 270 by spin coating without performing activation treatment (FIG. 2 (2 b)).

  Next, after the polyimide resin film 201 on the Si substrate 270 is bonded to the groove forming surface of the body plate 202 produced previously using the epoxy adhesive 241 (FIG. 2 (e)), the Si from the body plate 202 to the Si By separating the substrate 270, the polyimide film 201 and the Si substrate 270 can be easily peeled off (FIG. 2F), and after the Si substrate 270 is removed, the polyimide film 201 is fixed to the body plate 202 with an adhesive. (Fig. 2 (f)).

Thereafter, a liquid repellent film layer 228 is formed on the SiO ₂ film 243 on the discharge surface side of the body plate 202 by using Evaporation Substrate WR1 (water repellent film material for vacuum deposition), and the pressure chamber 224 portion is formed. A piezoelectric element 203 ′ having a thickness of 50 μm was attached to the covered nickel electroformed thin plate portion to complete the ejection head 20A (FIG. 2G).

  Next, the piezoelectric element 203 and the charging electrode 216 of the ejection head 20A are connected to an electrostatic voltage power source (electrostatic voltage 1.5 kV) and a drive voltage power source (drive voltage 20 V) including operation control means, and the ejection head 20A. The distance between the discharge surface and the counter electrode was set to 1 mm. After that, when the ejection head 20A was operated for about one month, the ejection of the ink droplets from the 32 ejection holes was not observed, and there was no inconvenience that the liquid volume was uneven or the liquid amount was uneven. It was confirmed to work.

It is a figure which shows an example of a structure of the liquid discharge head of this embodiment. It is a figure which shows typically an example which joins the body plate and thin plate which comprise the liquid discharge head of this embodiment. It is a figure which shows typically an example which joins the body plate and thin plate which comprise the liquid discharge head of this embodiment. It is a figure which shows typically an example which joins the body plate and thin plate which comprise the liquid discharge head of this embodiment. It is a figure which shows typically an example which joins the body plate and thin plate which comprise the liquid discharge head of this embodiment. 1 is a diagram illustrating an overall configuration of an example of a liquid ejection apparatus having a liquid ejection head that is an example of the present embodiment. FIG. 3 is a diagram illustrating an example of a configuration of a liquid ejection head that is an example of the present embodiment. It is a figure which shows the liquid discharge head for experiment used in order to examine the discharge conditions of a liquid. It is a schematic diagram which shows the electric potential distribution of the discharge hole vicinity of the nozzle by simulation. It is a figure which shows the relationship between the volume resistivity of a nozzle plate, and the electric field strength of a meniscus front-end | tip part. It is a figure which shows the relationship between a nozzle diameter and the electric field strength of a meniscus front-end | tip using the thickness of a nozzle plate as a parameter.

Explanation of symbols

213, 13 Discharge hole 210, 10 Nozzle 216, 16 Charging electrode 202, ₂ Body plate 243, 43 SiO ₂ film 224, 24 Pressure chamber (groove)
270 Holding substrate 201, 1 Thin plate (film)
241 Adhesive 203, 22 Piezo element 228, 28 Liquid repellent layer 20A, A Liquid discharge head S Liquid discharge device 3 Counter electrode E Operation control means 63 Electrostatic voltage power supply 61 Drive voltage power supply L Liquid D Droplet K Base material

Claims (13)

A nozzle for discharging liquid as droplets from the discharge hole;
A pressure chamber groove serving as a pressure chamber communicating with the nozzle;
A diaphragm covering the pressure chamber groove;
In the method of manufacturing a liquid ejection head having an electromechanical conversion element on the surface opposite to the pressure chamber groove side of the diaphragm,
A film forming step of the surface shape to form a film serving as the diaphragm in contact on the mirror surface of the holding substrate which is a mirror shape,
A bonding step of bonding a surface of the body plate in which the pressure chamber groove is formed with the surface on which the pressure chamber groove is formed and a surface on which the film on the holding substrate is formed;
Separated by peeling the supporting substrate from the film by separating the said holding substrate and the film have a a removal step of removing the holding substrate,
A method of manufacturing a liquid discharge head , comprising: providing the electromechanical conversion element on the film after the holding substrate is removed . The method of manufacturing a liquid ejection head according to claim 1, wherein the film forming step forms a metal film serving as the vibration plate on the mirror surface of the holding substrate . The method of manufacturing a liquid discharge head according to claim 1, wherein the film forming step forms a resin film made of polyimide resin to be the vibration plate on the mirror surface of the holding substrate . The film forming step forms a metal film to be the diaphragm on the mirror surface of the holding substrate,
The bonding step includes buffing each of the bonding surfaces of the metal film and the surface of the body plate where the pressure chamber grooves are formed to make the surface roughness Ra <10 nm. The method of manufacturing a liquid discharge head according to claim 1, wherein both polishing surfaces of the holding substrate are brought into contact with each other and pressure is applied to bond the two to each other. 5. The liquid ejection head according to claim 1, wherein an activation process for improving the adhesion of the film is not performed on the mirror surface of the holding substrate. 6. Production method. Method for manufacturing a liquid discharge head according to any one of claims 1 to 5, characterized in that the nozzle body plate, wherein the pressure chamber groove is formed is formed. A nozzle plate in which the nozzles are formed, the manufacture of liquid discharge head according to any one of claims 1 to 6, comprising a step of joining the body plate, wherein the pressure chamber groove is formed Method. It said body plate, method for manufacturing a liquid discharge head according to any one of claims 1 to 7, characterized in that it is formed from Si. On the surface discharge hole is present in the nozzle, method for manufacturing a liquid discharge head according to any one of claims 1 to 8, comprising a step of providing a SiO ₂ layer. The method of manufacturing a liquid discharge head according to claim 7 , wherein the nozzle plate is made of glass or resin having a volume resistivity of 10 ¹⁵ Ω · m or more. Method for manufacturing a liquid discharge head according to any one of claims 1 to 10 characterized by having a step of performing a liquid-repellent treatment on the outermost surface of the discharge hole of the nozzle is present. A liquid discharge head is characterized by being manufactured by the manufacturing method according to any one of claims 1 to 11. An electrostatic voltage applying means for generating an electrostatic attraction force by forming an electric field between the liquid in the nozzle and a substrate provided opposite to the surface on which the discharge hole exists; The liquid discharge head according to claim 12 .